W6 - Upper Motor Neurons Flashcards
UMN cell bodies lie in the Bst and cerebral cortex, what two things can the axons synapse with?
LMNs directly (rare) or local circuit neurons
What are UMN from the motor cortex responsible for?
Initiating and planning voluntary movements
UMN from Bst are responsible for…
Basic movements and posture
What does the cerebellum and basal ganglia do?
Regulate the descending tracts
Why do white matter tracts for UPM want to be as short as possible?
For efficiency
UMNs differ in where they what?
Terminate in the SC
What defines the Brodmann areas?
Cytoarchitecture
The dorsolateral prefrontal cortex (areas 9+46) are associated with …
Executive functions
What is the highest cortical area involved with motor planning of future movements?
Dorsolateral prefrontal cortex
The pre-motor cortex has sensory input from superior (touch) and ….. ….. lobe
Inferior (auditory) parietal lobe
What is the main aim of the input to the pre-motor cortex? (areas 6+8)
Motivation for the desired outcome
Where is the primary motor cortex located?
Pre-central gyrus in Brodmann’s area 4
UMN from primary MC have thick axons, what does this mean about their connections with LMNs
The connections are strong
What type of pyramidal cells are the largest neurons in the human CNS and account for ~5% of projection to the SC?
Betz cells
Where are pyramidal cells found? (the UMN of the primary MC)
Cortical layer 5 of the primary motor cortex
Corticobulbar axons leave the CBT at different levels of the brainstem what are these?
CN nuclei, reticular formation (for wakefulness) and nuclei at base of pons
Describe the pathway of neurons in the CBT and CST
Internal capsule - cerebral peduncle - pons - pontine fibres
What are the two CSTs?
Lateral (~90%) and ventral (~10%)
Where do the CS axons decussate to form the Lat CST in the CS?
Caudal medulla
The ventral CS axons do not what?
Decussate in the caudal medulla
Which CST are involved in innervates the muscle/hand and which serve the axial/proximal limb muscles?
Lateral - hand/forearm, Ventral - axial/proximal limbs
Where are spinal local interneurons found?
Lateral horn of SC
